Within-class teacher-pupil ratios: the current position
International perspectives
The case for smaller class sizes

This briefing:

  • describes the current position on pupil-teacher ratios in the UK;

  • examines evidence related to within-class pupil-teacher ratios in this country and elsewhere; and

  • sets out the educational case for smaller class sizes.

Within-class teacher-pupil ratios: the current position

Currently, stipulations concerning in class teacher-pupil ratios in the UK, apart from in Scotland, are established through regulations rather than as express terms in teacher and school leader contracts of employment.

In England and Wales, legislation sets out class size maxima for five to seven year olds, currently 30 pupils per class with some exceptions, but not for the remaining years of primary, pupils aged seven to 11, or for secondary education, pupils aged 11 to 19.

Legislation in Northern Ireland sets out class size maxima for four to eight-year-olds of 30 pupils per class but not for the remaining years of primary education, pupils aged eight to 11. There is no legislation governing class size maxima in post-primary education, pupils aged 11 to 18, apart from regulations governing maximum class sizes of 20 pupils per teacher in practical subjects, which include science, technology and design, home economics, art and design, physical education and music. Further information can be found on our Class Sizes in Northern Ireland page.

In Scotland, the Scottish Negotiating Committee for Teachers (SNCT) Handbook sets out contractual maximum class sizes, although some additional provisions are set out in regulations.

Current arrangements in Scotland


25 pupils

Circular 1/2007


30 pupils

Education (Lower Primary Class Sizes)(Scotland) Regulations 1999 as amended


33 pupils

SNCT Handbook

Mixed age classes

25 pupils

SNCT Handbook



33 pupils

SNCT Handbook


30 pupils

SNCT Handbook

Practical classes [1]

20 pupils

SNCT Handbook


Additional support needs arising from

Number of pupils

Moderate learning difficulties


Profound learning difficulties

10 [2]

Severe physical impairment


Severe learning difficulties


Significant hearing impairment


Significant visual impairment


Language and communication difficulties


Social, emotional and behavioural difficulties


Source: SNCT Handbook

The average figures cited above mask significant degrees of variation in class sizes across the UK. Data from the most recent School Census in England for 2021/22 confirms that there are nearly 1,800 Reception and Key Stage 1 classes above the statutory limit of 30 pupils per class. At Key Stage 2, more than 16% of pupils are taught in classes of 31 pupils or more. More than 13% of secondary pupils are taught in 13,500 such classes.

Similar examples of large class sizes are evident elsewhere in the UK. In Wales, six per cent of infant pupils in 2022 were educated in classes of 31 pupils or more, with more than 12% of junior pupils educated in classes of this size.

However, in Scotland, where class size limitations are relatively more extensive, large classes are less prevalent. In 2021, only 97 children in P1-P3 were educated in classes with 31 or more pupils.

International perspectives

Most education systems across the Organisation for Economic Co-operation and Development (OECD) have some statutory limits or official guidelines on class size. New Zealand, Finland and Sweden are notable exceptions to this, although it should be recognised that in Finland and Sweden, class size maxima are often set by local authorities rather than at national level.

Many of the education systems often cited by UK policymakers as high performing or fast improving have also taken steps, either through laws or guidelines, to establish maximum class sizes:


Class size maxima (primary unless stated)


40 (Education Ministry guidelines)



South Korea

35 (Education Ministry guidelines)

Hong Kong

36 (lower secondary)


17-23 (depending on age group)

British Columbia




New South Wales




Jurisdictions such as Singapore, Japan, South Korea and Hong Kong that have traditionally been tolerant of large in-class pupil-teacher ratios, have begun to devote significant attention to the merits of limiting class sizes.

Relative to other OECD countries, class sizes in the primary sector in the UK are high. The average primary class size in the UK was 27 in 2017, the latest year for which figures are available, compared with an OECD average of 21.

The case for smaller class sizes

Policies seeking to impose limits on class sizes have tended to be based on one or more of the following rationales:

  • smaller class sizes support learner progress and achievement;

  • smaller class sizes can support action to reduce teacher workload and improve working conditions;

  • smaller class sizes are valued by parents; and

  • smaller class sizes ensure that teachers and pupils can teach and learn in safe, educationally conducive environments.

Supporting learning

There is a compelling case that smaller class sizes promote more effective teaching and learning. This view is based on the premise that smaller class sizes allow more individual attention to be given to pupils through, for example, providing increased opportunities for one-to-one or small group feedback. It is also suggested that the more personalised approaches to teaching and learning that small class sizes support reduce the amount of teaching time spent managing pupil behaviour.

These perspectives have, for example, underpinned moves to reduce class sizes in Scotland and are frequently cited as policy drivers (pdf) in other jurisdictions that have introduced mandatory limits on class size.

It has been asserted that class size has a negligible impact on pupil progress and achievement. For example, the former Coalition Government insisted (pdf) that ‘more effective [education] systems tend to have fewer, better teachers through having larger classes…’

Such assertions are difficult to sustain on the basis of available evidence. It has been suggested, for example, that because class sizes in education systems identified as high performing, such as Hong Kong, Singapore and Japan, are relatively large, it is possible to conclude that class size is not related to pupils’ educational outcomes. However, these studies often fail to consider other influences on educational performance, including high levels of parental support, cultural factors that favour education and the prevalence of private tutoring. It is therefore inappropriately simplistic to deny the influence of class size on this basis alone.

Many of the critiques of action (pdf) to reduce class sizes are based on metastudies of existing research, include studies of varying quality, adopt different methodological techniques and consider pupils of different ages. This feature of metastudies on class size calls into doubt the validity and reliability of their conclusions. All the principal studies that refute the importance of class size are based on secondary data and very few, if any, have involved primary research on the impact of class size in practical contexts.

It is also important to note that studies critical of the relationship between class size and the quality of pupils’ educational experience are based on statistical analyses of quantitative pupil performance data, usually obtained through testing. Therefore, they fail to reflect the implications of class size for other dimensions of teaching and learning, such as the nature of pupil-teacher interaction or the range of pedagogical approaches from which teachers can choose. They also cannot capture the implications of class size for pupil progress and achievement in areas of learning not assessed by the tests upon which their quantitative analyses rely.

Studies that avoid these limitations appear to indicate that limiting class size can have a powerful impact on pupils’ educational experiences. The Student/Teacher Achievement Ratio (STAR) project in Tennessee and the Class Size and Pupil-Adult Ratio (CSPAR) study in the UK, both of which were based on primary rather than secondary research, supported the view that class size had positive implications for pupils’ learning, particularly for younger pupils, those from disadvantaged backgrounds and those with relatively lower levels of prior attainment. Other studies have pointed to the benefits for the development of pupils’ non-cognitive skills (such as persistence and engagement) of smaller class sizes.

Evidence based on primary research also suggests that smaller class sizes can have positive benefits for Black pupils and for those for whom English is an additional language (pdf).

While a substantial quantity of research has centred on the particular benefits of smaller class sizes for distinct categories of learner, such as those in the first years of compulsory education, credible studies have also indicated that reductions in class size can represent an effective intervention for all students, regardless of age.

Positive impacts on workload and working conditions

Literature reviews of teachers’ reported experience (pdf) confirm that reductions in class size can have a positive impact on teacher workload and levels of stress. This is to be expected, given that teachers in the UK and elsewhere report excessive class size as a key driver of excessive workload. Teachers report consistently that smaller class sizes reduce burdens in relation to planning, assessment, marking and record keeping.

Evidence from other jurisdictions (pdf) further suggests that reductions in class size can also have a positive impact in addressing issues of teacher recruitment and retention.

Parental support

In general, evidence suggests that parents place significant emphasis on class size. Research conducted in the UK indicated that three quarters of parents knew the exact number of pupils in their child’s class. Around six in ten parents believe that there are an excessive number of pupils in their child’s class, while over 96% of parents believe that the number of children in a class influences the quality of children’s educational experience. Studies in other jurisdictions also reflect the importance placed by parents on the issue of class size.

A poll conducted for the Independent Schools Council, cited in Department for Education research (pdf), highlighted class size as a reason why parents may express a preference for schools in the independent sector. A quarter of respondents to this survey stated that a key reason for this preference was the relatively smaller class sizes found in the independent sector.

Ensuring safe environments conducive to learning

The NASUWT continues to highlight the health and safety dimensions of class size, although the Union has emphasised, in this context, that the solution to managing class size issues will be unique to each school. Addressing problems of excessive class size is clearly relevant in the context of statutory provisions for securing the health, safety and welfare of staff and pupils in schools. It also creates a physical environment in which pupils and teachers are able to focus on learning and teaching.

In Scotland, the importance of class size and health and safety issues is reflected in the provisions of the Schools General (Scotland) Regulations 1975, which set limits on pupil numbers on a whole school and individual class basis.

In some schools, different class sizes apply in different rooms in an individual school because of room size. In practice, determinations of class size begin with an assessment based on health and safety considerations, before other factors, such as contractual limits are taken into account, so that a class may have a limit set on its size that is lower than that provided for in the SNCT Handbook as a result of the provisions of the 1975 Regulations.

The NASUWT has published more detailed Class Sizes Guidance on the health and safety dimensions of class size issues.

[1] For the purposes of the SNCT, practical classes are those in the following lessons: administration, art and design, biology, chemistry, craft and design, engineering, general science, graphic communication, home economics, land and environment, managing environmental resources, physics, practical craft skills, product design and technological studies
[2] This limit is based on the understanding that in such classes, teachers work alongside support staff with an overall pupil/adult ratio of 1:2.5


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